The objective of this research proposal is to study the effects of malnutrition early in life on mental development and to establish to what extent it is possible to reverse or prevent intellectual retardation by food supplementation programs. Malnutrition is known to be associated with impaired psychological function. This relationship is confounded, however, by health and social factors that covery with nutrition and may themselves affect the psychological development. To investigate these complex relationships we have undertaken a prospective maltidisciplinary intervention study of children at risk of malnutrition starting at six months of gestation. After sample selection, families are assigned at random to six study groups: A) No supplementary feeding; B) Supplementary feeding from six months to 3 years of age; C) Supplementary feeding from 6 months of gestation to 6 months of age; D) Supplementary feeding from 6 months of gestation to 3 years of age; A-1) A home intervention program designed to increase psychological stimulation of the child but no supplementary feeding; D-1) Supplementary feeding from 6 months of gestation to 3 years of age plus psychological stimulation. All groups are given a uniform obstetrical and pediatric health care program. Subjects are observed longitudinally for three years by repeated measurement of nutritional status, intellectual functioning and a number of concomitant social and health variables. This experimental design is expected to yield information on the relative effects of malnutrition at different ages on intellectual functioning. It will also be possible to determine the effects of food supplementation programs of varying duration and starting at different points of life on physical growth, health, and intellectual development. Groups A, A1, D, and D1 constitute a two-component factorial experiment that allows assessment of simple and interactive effects of supplementation and stimulation. Groups A, B, C, D permit study of the effects of supplementation at different age levels. Group A by itself constitutes an ecological study of malnutrition since the only intervention it receives is free medical caree and measurements. BIBLIOGRAPHIC REFERENCES: Christiansen, N., and Herrera, M.G. Problems in sibling matching designs: A case report. Ecology of Food and Nutrition 4:1-6, 1975. C (Text Truncated - Exceeds Capacity)